First of factor the common term 3a
3a(2a+7)/ 3a^2-----------> [tex] \frac{3a(2a+7)}{3a^{2} } [/tex]
cancel out the 3
a(2a+7)/a^2---------------> [tex] \frac{a(2a+7)}{ a^{2} } [/tex]
simplify
2a+7/a----------------------> [tex] \frac{2a+7}{a} [/tex]
You are done
Hope this helps :)